Analgesic Therapy in Postherpetic Neuralgia: A Quantitative Systematic Review

Background: Postherpetic neuralgia (PHN) is a complication of acute herpes zoster, which is emerging as a preferred clinical trial model for chronic neuropathic pain. Although there are published meta-analyses of analgesic therapy in PHN, and neuropathic pain in general, the evidence base has been substantially enhanced by the recent publication of several major trials. Therefore, we have conducted a systematic review and meta-analysis for both efficacy and adverse events of analgesic therapy for PHN. Methods and Findings: We systematically searched databases (MEDLINE 1966–2004, EMBASE 1988–2004, CINAHL 1982–2002, and PubMed [29 October 2004]) for trials of PHN. We also searched references of retrieved studies and review articles for further trials. We included trials that examined adult patients with PHN of greater duration than 3 mo, that were blinded, randomised, and had at least one measure of pain outcome. Dichotomous pain outcome data were extracted for 50% decrease in baseline pain using a hierarchy of pain/pain-relief measurement tools. Where available, dichotomous data were also collected for adverse events. Calculated estimates of efficacy included relative benefit and number needed to treat. Conclusion: The evidence base supports the oral use of tricyclic antidepressants, certain opioids, and gabapentinoids in PHN. Topical therapy with lidocaine patches and capsaicin is similarly supported. Intrathecal administration of methylprednisolone appears to be associated with high efficacy, but its safety requires further evaluation. A systematic review of the evidence for treatment of postherpetic neuralgia summarises the therapies that seem to be most effective. Background: Postherpetic neuralgia (PHN) is the pain that people sometimes get after shingles. It can be severe. Although many treatments have been tried for it, doctors do not agree on how to best treat it. What Did the Researchers Do?: They looked systematically to find all the trials that have investigated treatments for PHN. They assessed each trial to see if it could provide useful results—e.g., if it was well designed, clear that they were treating patients with PHN, and that clear results could be taken from the trials. They also looked to see if the trials had assessed the possibility that the treatments could cause harm. What Do These Results Mean?: This type of review is the most reliable form of evidence that doctors have available to them in deciding on treatment. Even so, the results are not conclusive. Future trials should be designed rationally to fill in the gaps of knowledge about the possible treatments for this disorder. In the meantime, however, there are some drugs that seem to work relatively well, and, outside of a clinical trial, these drugs should be used first. Where Can I Get More Information?: Medline Plus discusses shingles and neuralgia more widely: